Generate list of names based on multiple criteria

Please see the attached spreadsheet. Table 1 is Fill, Table 2 is Vol, and Table 3 at the bottom is simply a sumif based on values in table 1 and 2. My end goal is hard to explain, so I'll give an example.

I want the output to be something like this:

Group 1:
A, D, F
1, 10, 15, 20, 25

Condition for group 1 is that Total Vol for A, D, F is at least 70% of original if still faced 1-30

So what I'm trying to do is identify values in 1-30 that A-I have in common, and by grouping them together the average Fill would increase without decreasing the total Vol amount too much.

I understand this may be confusing, so please let me know if this isn't clear. Thank you so much!